During the initial phase of this investigation we found functional changes in the microcirculation of rats made diabetic with the intravenous administration of streptozotocin. This finding parallels the clinical observations of other investigators who reported similar functional changes in humans suffering from diabetes mellitus. Our investigation is extended in two directons: 1) The quantitative description of the functional changes in capillary permeability to macromolecules. 2) In cooperation with Dr. P.S. Roheim of the Albert Einstein Medical College in New York City we will study the apolipoprotein permeability of the capillaries in order to evaluate potential changes in lipoprotein metabolism and atheroma formation in diabetic animals. BIBLIOGRAPHIC REFERENCE: Capillary Permeability to Albumin in Subclinically Diabetic Rats. Stork, J.E., Cook, V.L., Fajer, A.B., Pinter, G.G., Fed. Proc. 35 316 1976 (Abstract).